This research will develop an electrotactile haptic display to present computer graphics to blind persons. The increasing use of computer graphics and pictorial displays (such as the Macintosh and Microsoft Windows environments) presents a major problem for blind computer users. While text output is available through Braille, Optacon (optical-to- tactile converter), or speech synthesis, none of these techniques are suitable for presentation of complex pictorial or spatial information (organizational charts, computer program or process flowcharts, electrical, architectural, or mechanical drawings, three-dimensional graphs, pictures, visual artwork). The proposed investigations will create a flat, smooth tablet with embedded electrodes and external driver circuitry that can electrically display pictorial information from a computer directly to the skin. A blind user will then be able to interpret the properly-formatted percepts that s/he acquires by scanning the display with the fingertips. Exploratory research during Year 1 will extend present electrotactile knowledge to electrical stimulation of touch on the fingertip. Studies will determine the stimulation mode (direct afferent nerve stimulation or indirect electrostatic/mechanical stimulation), electrode geometry, and waveform characteristics that produce strong, repeatable, and comfortable single-point stimulation. Year 2 efforts will develop a small two-dimensional fingertip-scanned (haptic) display. Basic perceptual studies with this two-dimensional display will likely suggest further improvements in electrode geometry or driving waveform. During Year 3, this display (with associated electronics and control software) will grow at least ten times larger so that complex geometric and pictorial information from a computer screen can be displayed. Extensive perceptual studies during Year 4 will test the hypothesis that complex pictorial information is more readily perceived by haptic exploration with the fingertips than through a fixed-location 384-point electrotactile display on the abdomen (currently-available technology). Research during Year 5 will explore the feasibility of other rehabilitation applications, including retraining the visual perception of individuals with stroke-induced visual agnosia (intact eye and optic nerve), and dyslexia. We hypothesize that simultaneous display of "visual" information tactually and visually (on a computer screen), in conjunction with the user's properly-functioning tactile perceptual system, can cause functional reorganization of the damaged visual processing areas of the brain, effecting improved visual perception.